214 LIFE IN NATURE. 



be perceived by us through either of two causes : 

 either a change apart from us, presenting the same 

 existence differently : or a change affecting our- 

 selves, and placing us in different relations to that 

 existence. 



It is our nature that by changes of our own con- 

 dition we are made to feel as if other changes were 

 occurring before us. In those dioramas, for ex- 

 ample, in which the picture is fixed and the spec- 

 tators are carried round, the impression upon them 

 is precisely the same as if the scene moved before 

 their eyes : nor is it possible for them to obtain any 

 other. In a similar way, we are conscious of per- 

 ceiving a succession of light and darkness of day 

 and night while there is truly no such succession. 

 There is a space illuminated by the sun's rays, and a 

 shadow cast by the earth : our succession of day and 

 night is but our being carried alternately from one 

 into the other. In this case all men receive the 

 same impression of external sequence from a change 

 which affects them all. 



It is clear, therefore, that a change affecting all 

 men in common would perfectly account for the fact 



